TWO-MATERIAL BASE FOR A DATA STORAGE SYSTEM
An enclosure system includes a motor assembly that has a motor magnet and at least one motor coil. The enclosure system also includes a base coupled to the motor assembly. The base includes a first portion that includes a non-magnetic material and a second portion that includes a magnetic material. The first portion of the base is in closer proximity to the motor magnet than the second portion of the base.
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The present invention relates generally to a base, and more particularly but not by limitation to a base coupled to a motor assembly.
BACKGROUND OF THE INVENTIONA typical data storage system includes a rigid housing having a base and top cover that encloses a variety of components. The components include one or more discs having data surfaces for storage of digital information. The disc(s) are mounted on a spindle motor. The spindle motor causes the disc(s) to spin and the data surfaces of the disc(s) to pass under respective aerodynamic bearing disc head sliders. The sliders carry transducers, which write information to and read information from the data surfaces of the discs.
Recently, there has been a rapid increase in the production of smaller and lighter weight disc drives in the disc drive industry as well as a rapid increase in the areal density of disc(s). These smaller sized disc drives are for use with handheld or portable devices, such as cell phones and digital music players, which are energized by a battery. When producing smaller sized disc drives for portable devices, it is often desirable to include a spindle motor with a high electromagnetic (EM) performance level. Spindle motors having high EM performance levels include low power consumption, a high torque constant (Kt) and a high voltage margin at low temperatures (to overcome start up problems).
In addition, it is desirable to include spindle motors that have small z-heights and fluid dynamic bearings (FDB). Small z-heights allow the disc drive to be as small as possible for use in portable devices. Fluid dynamic bearings in a spindle motor generate much less vibration in comparison to conventional ball bearings. However, spindle motors, having fluid dynamic bearings, consume much more power than that of spindle motors having conventional ball bearings. In general, the power consumption of fluid dynamic bearings can consume 1.5 to 2.0 times more power than conventional ball bearings. Although the use of fluid dynamic bearings in a spindle motor are desirable, the large power consumption of fluid dynamic bearings compromises EM performance levels in the spindle motor.
Embodiments of the present invention provide solutions to these and other problems, and offer other advantages over the prior art.
SUMMARY OF THE INVENTIONAn enclosure system includes a motor assembly that has a motor magnet and at least one motor coil. The enclosure system also includes a base coupled to the motor assembly. The base includes a first portion that includes a non-magnetic material and a second portion that includes a magnetic material. The first portion of the base is in closer proximity to the motor magnet than the second portion of the base.
The base includes an inner surface and an outer surface. The inner surface includes a first section that includes the first portion of the base. The inner surface also includes a second section that includes the second portion of the base. The motor magnet includes a dimension that faces the inner surface of the base. The first section of the inner surface corresponds with at least the dimension of the motor magnet that faces the inner surface.
Other features and benefits that characterize embodiments of the present invention will be apparent upon reading the following detailed description and review of the associated drawings.
Disc drive 100 includes a housing 102 having a cover 104 and a base 106. As shown, cover 104 attaches to base 106 to form an enclosure 108 enclosed by a perimeter wall 110 of base 106. The components of disc drive 100 are assembled to base 106 and are enclosed in enclosure 108 of housing 102. As shown, disc drive 100 includes a disc or medium 112. Although
In the example shown in
In general, there are two types of bases that can be used to produce smaller sized disc drives. One type of base is an aluminum base casting, while another type of base is a stamped steel base. Both types of bases utilize machining technologies. In either type of base, spindle motor assembly 114 is integrated into base 106. Often, a stamped steel base is the type of base chosen for producing smaller sized disc drives. A stamped steel base has a high stiffness and can be made of a soft magnetic material to protect a read/write head, especially perpendicular recording read/write heads, from external magnetic fields. An aluminum base casting does not demonstrate these desirable traits. An aluminum base casting does not provide sufficient magnetic shielding, it has a low stiffness and more drive parts which takes more space and results in higher drive part cost.
Even if base 106 is made of the more desirable stamped steel base and also a soft magnetic material, spindle motor assembly 114 can still experience an undesirably low electromagnetic (EM) performance. For example, spindle motor assembly 114 can experience a high bearing friction that results in a high power consumption, a low torque constant (Kt) as well as a start up problem at low temperatures. The cause of the low EM performance is that the space between soft magnetic base 106 and motor magnet 148 is too small. Magnetic flux will not only travel through stator teeth 144 but will also have a high attraction force between motor magnet 148 and soft magnetic base 106. This results in a much higher bearing friction and, hence, a much higher power consumption and a much lower torque constant (Kt) of the spindle motor.
To increase the space between soft magnetic base 106 and motor magnet 148, either motor magnet 148 can become thinner or a z-height of spindle motor assembly 114 can be increased. As previously discussed, when producing smaller sized disc drives, a small z-height of spindle motor assembly 114 should not be sacrificed. In the alternative, thinning motor magnet 148 is also detrimental. A thin motor magnet will result in low EM performance. For example, spindle motor assembly 114 would suffer from high power consumption, a low Kt and a low voltage margin under low temperatures (i.e. a start up problem).
Instead of increasing the space between soft magnetic base 106 and motor magnet 148 by thinning motor magnet 148 or increasing the z-height of spindle motor assembly 114, embodiments of the present invention utilize a two material system for the base plate to solve EM performance problems. One of the materials is a non-magnetic material and the other one of the materials is a magnetic material. In accordance with one embodiment,
Stator teeth 144 extend from stator rim (not illustrated in
In the embodiment illustrated in
In
In the embodiment illustrated in
In accordance with another embodiment,
Stator teeth 144 extend from stator rim (not illustrated in
In the embodiment illustrated in
In
In the embodiment illustrated in
It is to be understood that even though numerous characteristics and advantages of various embodiments of the invention have been set forth in the foregoing description, together with details of the structure and function of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail, especially in matters of structure and arrangement of parts within the principles of the present invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. For example, the particular elements may vary depending on the particular application for the enclosure system while maintaining substantially the same functionality without departing from the scope and spirit of the present invention. In addition, although the preferred embodiment described herein is directed to a base for data storage system, it will be appreciated by those skilled in the art that the teachings of the present invention can be applied to other types of enclosure systems, without departing from the scope and spirit of the present invention.
Claims
1. An enclosure system comprising:
- a motor assembly having a motor magnet and at least one motor coil; and
- a base coupled to the motor assembly and having a first portion comprising a non-magnetic material and a second portion comprising a magnetic material, wherein the first portion is in closer proximity to the motor magnet than the second portion.
2. The enclosure system of claim 1, wherein the magnetic material of the second portion comprises a soft magnetic material.
3. The enclosure system of claim 1, wherein the first portion and the second portion of the base are formed by metal injection molding the base.
4. The enclosure system of claim 1, wherein the base further comprises an inner surface and an outer surface.
5. The enclosure system of claim 4, wherein the first portion of the base is included in a first section of the inner surface of the base, extends a thickness of the base from the inner surface to the outer surface and is included in a first section of the outer surface of the base.
6. The enclosure system of claim 4, wherein the second portion of the base is included in a second section of the inner surface of the base, extends a thickness of the base from the inner surface to the outer surface and is included in a second section of the outer surface of the base.
7. The enclosure system of claim 4, wherein the first portion of the base is included in a first section of the inner surface of the base and extends a partial thickness of the base from the inner surface towards the outer surface of the base.
8. The enclosure system of claim 4, wherein the second portion of the base is included in a second section of the inner surface of the base, extends a thickness of the base from the inner surface to the outer surface and is included in the outer surface of the base.
9. The enclosure system of claim 1, wherein the motor assembly and the base are included in a data storage system.
10. An enclosure system comprising:
- a base having a first portion comprising a non-magnetic material and a second portion comprising a magnetic material, the base including an inner surface and an outer surface;
- a motor assembly coupled to the base and having a motor magnet and at least one motor coil the motor magnet having a dimension that faces the inner surface of the base; and
- wherein the first portion of the base is included in a first section of the inner surface of the base that corresponds with at least the dimension of the motor magnet that faces the inner surface.
11. The enclosure system of claim 10, wherein the motor assembly further comprises a motor stator that supports the at least one motor coil and includes an inner diameter that is spaced apart from and surrounds the motor magnet.
12. The enclosure system of claim 11, wherein the first portion of the base is included in a first section of the inner surface of the base that corresponds with at least the inner diameter of the motor stator.
13. The enclosure system of claim 12, wherein the second portion of the base is included in a second section of the inner surface of the base that is outside the corresponding inner diameter of the motor stator.
14. The enclosure system of claim 10, wherein the first portion of the base is in closer proximity to the motor magnet than the second portion of the base.
15. The enclosure system of claim 10, wherein the first portion and the second portion of the base are formed by metal injection molding the base.
16. The enclosure system of claim 15, wherein the first portion of the based bonds to the second portion of the base by sintering the first portion and the second portion together.
17. A base for a data storage system comprising:
- a first portion comprising a non-magnetic material and included in a first section of an inner surface of the base;
- a second portion comprising a magnetic material and included in a second section of the inner surface of the base; and
- wherein the first portion is configured to be in closer proximity to a motor magnet of a motor assembly coupled to the base than the second portion.
18. The base of claim 17, wherein the first portion is included in a first portion of the outer surface of the base.
19. The base of claim 17, wherein the first portion extends a thickness of the base from the inner surface to the outer surface.
20. The base of claim 17, wherein the first portion extends a partial thickness of the base from the inner surface towards the outer surface.
Type: Application
Filed: Jul 19, 2006
Publication Date: Jan 24, 2008
Patent Grant number: 7692892
Applicant: SEAGATE TECHNOLOGY LLC (Scotts Valley, CA)
Inventors: Mo Xu (Watsonville, CA), Niroot Jierapipatanakul (Singapore), Wei Rhen Spencer Hoon (Singapore)
Application Number: 11/458,455
International Classification: G11B 17/02 (20060101);